My invention is a unique nut for repairing the leaking connection between an automobile air conditioning cooling coil and its expansion valve.
Many automobile air conditioning units on the road today as well as air conditioning units being manufactured include an evaporator or cooling coil which is connected to the unit's expansion valve by a steel nut. The nut is irremovably joined to the cooling coil by an annularly flanged pipe.
As the air conditioning unit is assembled in the automobile, a gasket is placed over the end of the coil's flanged pipe and the steel nut is pushed against the flange on the pipe and threaded over the male thread on the pipe leading into the expansion valve. As the end of the expansion valve's pipe fits over the gasket and contacts the cooling coil pipe's annular flange, a leak-proof connection is established between the cooling coil and the expansion valve.
During normal operation of the automobile's air conditioning unit, the connection between the cooling coil and the expansion valve is subject to periods of extreme cold which causes condensation of moisture and formation of ice on all surfaces of the steel coupling nut. The alternate freezing and drying of the nut causes rust to form on the threads and other surfaces of the nut until the connection is no longer leakproof. Eventually the air conditioning system loses pressure, and the system fails to operate.
Since the faulty rusted nut cannot be replaced by a similar new nut due to the annular flange on the cooling coil pipe, the system can be made operative only by disconnecting the entire cooling coil from the system and replacing it with a brand new cooling coil and its irremovable new nut. The cost in materials and labor for this conventional repair runs several hundred dollars.
My invention provides a new method of repairing an air conditioning system embodying an irremovable nut on the cooling coil by use of a unique clamp-on coupling nut.
My coupling nut is preferably formed from single piece of brass or bronze. The main body portion of the nut has a flat front face and essentially square sides. Opposite the nut's front face is a hexagonal shank. An axially bored cylindrical passageway extends through the hexagonal shank and opens into a larger cylindrical passageway through the main body of the nut. This passageway is threaded to accomodate the male threaded end of the air conditioner's expansion valve pipe.
The diameter of the cylindrical passageway in the nut's shank is sized to snugly fit around the cooling coil's pipe and the joinder between the shank's passageway and the larger passageway in the main body of the nut is smoothly curved to conform to the surface of the annular flange on the cooling coil.
Two holes are bored, threaded and countersunk in the main body of the nut running perpendicular to the passageways through the nut on opposite sides of the passageway in the main body. Then the nut is cut in two along a line passing through the center line of the passageways through the nut, creating two mirror-image halves.
My inventive method of repairing an air conditioning system which has failed because of a leaking coupling nut comprises cutting off the failed rusty steel nut and removing it from the ends of the cooling coil pipe and the expansion valve pipe. Then with the gasket in place over the end of the cooling coil pipe and the end of the expansion valve pipe pressed against the flange on the cooling coil pipe, the two halves of the coupling nut are placed around the abutting ends of the pipes and the two halves firmly joined together by two Allen head screws inserted into the two countersunk holes in the main body of the nut. The joinder between the two pipes can be made more secure by turning the coupling nut by use of a wrench on the hexagonal shank of the nut.
The clamped together coupling nut thus provides a secure leak-proof seal between the cooling coil and the expansion valve which does not malfunction in use and which, being made of non-ferrous material, will not corrode and eventually fail as is very often the case with the original steel clamping nut.